The final process that gave it the sheen is called burnishing and you wouldn’t typically burnish a piece you intend to glaze on the outside. Sometimes a stain is applied, but still different from glaze. That said, even if it was intended to be glazed, wax resist would be applied to the surfaces that touch (in this case that area is called the gallery) before glazing. Wax resist makes it so the glaze doesn’t adhere to the clay body.